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H. R. DAVIES ELECTRICAL SYSTEM May 1, 1928.

Original Filed Feb. 13, 1918 o 5 Il/IlllI/NIII awwmtqz Henry R. Dawes 3% W W Patented May I, 1928.

1,668,056 PATENT OFFICE.

HENRY-R. navms," or roar-mo, euro, assrenoa, my mum assremms, are an anacrarcau'ro-m'm conrm, or romeo, onroga coaroaa'rrou-or onro.

mmersion. srsrm.

' Application m ca 'l'eb'nary 1a, 1o1s, Serial No. 216,853. Renewed an 10, 621.. Serial it. mp4s.

This invention relates to electrical systems containing a plurality of circuits each of which is electrically associated or connected with the other circuit orcircuits.

In general terms, the invention is comprehended in the utilization, in conjunction with a given circuit orcircuits of a modify-.

ing or'control circuit which isreferably,

although not necessarily indepen ent of the In other circuits and which has an inductive influence on said circuits to control the current fiow'and other electrical .conditions of the other circuits. Preferabl the invention is embodied in a short'circu ted coilwound in 16 ductively, the total capacitance of the circuit being appreciably less than that of the other circuits and combiningwith the inductance ofthe coil to give a natural period of oscillation to the circuit less than that of 20 the, other circuits. This coil is laced in inductive relation to a portion -o .the circuit,

the current or other 'electrical characteristics of which is to be modified, the coil operating to suppress or modify the current, in the other circuits havin currents therein oscillat-ing at frequencies below, the natural period, asdetermined by its inductance and ca acitanc'e,of the control coil.-

ore specifically the invention relateslto an electric, circuit having utility in connection with i nition system for automobiles.

In electrical circuits in which oscillating currents flow, it is advantageous at times to suppress or diminish currents of a certain as frequency without, at-the same'time, hindering or modifying circuits of other frequencies; In igmtion systems for automobiles, for example, in order to' have sufficient current for the higher speeds of operation of 40 the system, it is desirable that the conductive resistance of the circuit be diminished to a 'point where thdcurrent' available at the highest speed is adequate. This decrease in resistance, however, would permit'currents' of too high value to flow at the lower frequencies which might cause injury to theIcircuits; and to ofiset this condition, means i should be provided for automatically sup-' pressing or hindering the current flow at the i lower frequencies.

It is an object, therefore, of the present invention to provide a' means for electrical circuits which is efiective at lower frequencies only to' reduce the current flow in the cir,

cuits.- It is another object of the invention .a storage battery 2, and furnish current for to provide automatic control means for alternating currents flowing ,in an electrical circuit which is operative only at orbelow a given frequency. of alternation. Still another object of the invention is to provide a new and improved form of ignition for internal combustion: engines, which is suitable, and. res onsive --to modern requirements.

A'not ler object of the invention is to provide a type ofignition which automaticall compensates-for the increased inductive e 5 fects of the circuit at high speeds, thereby maintaining an approximately even current value in the secondary spark plug circuit through wide variations of enginespeed.

' Further objects, and objects relating to economies of manufacttire and details of construction will definitely appear from thedetailed description to follow. A structure and arrangement constituting an. embodiment of my invention which may be preferred is illustrated in connection with an ignition system in the accompanying second modification of the similar parts throughout the several views;

In the ignition system illustrated dia rammatically in Fig; I, the numeral 1 designates an electric generator adapted-to charge the ignition circuit. The generator is of the regulated typeand is here shown'as a thlrd .brush generator having a shunt field 3, connected to a main brush 4, and a third auxiliary brush 5. Intermediate the storage battery which is connected across the mains in parallel with the load 6, and the nerator 1, is a reverse current cut-out wit the usual shunt coil 7 series coil 8, core 9, armaturelt). and contacts 11 and A switch 13 1s placed 'in the load circult.

' The ignition circuit comprises the interrupter 14, rotatable cam 15, condenser 15' connected in parallel with the interrupter,

switch 16, and primary induction coil wind- 11c .ed at one end and "at its other end is connected to the distributor arm 19, through which connections to the various spark plug circuits 20, 21, 22 and 22, are made. A choke coil comprising'a short-circuited winding 24 is associated with the windings 17 and 18.

'Various methods of applying the different windings may be er nployed, the results obtained being similar. In the method illustrated in Fig. II, the three windings are wound on a common core, which effects a greater economy in metal and decreases the inductive lag athigh frequencies. In Fig.

" III a closed magnetic circuit 25 is shown,

as a control medium, irrespective of the mcanshy which the alternations-of the priwith thechoke coil 24 separated from the' induction coil proper; and in Fig. IV a'similar closed magnetic circuit 26 is shown, with the primary and secondary separated to different portions of the circuit, and the choke coil 24 placed adjacent to the primary winding. Instead of employing a closed magnetic circuit as shown in Figures III and "IV, a partly closed circuit, or a circuit in which a portion has small cross-sectional area, may be used.

In ignition systems where the source of current is maintained at approximately constant potential, as in the battery system, a serious difficulty in the ignition at high frcquencies arises due to the inductive lag and consequent decrease in effective current in the primary at the break of the interrupter contacts. To design the ignition coil for the obtainable high speed currents-without addi-- tional controlling devices, would be impracticable as at low frequencies serious heating effects would result. To avoid this difliculty, I have provided a choke coil with a determined time constant such that at low-s eeds.

the primary current is effectively cut own.

At the higher speeds, however, the choke coil gradually becomes ineffective at the instant of break, thereby permitting normal operation of the induction coil. It is obvious that the time constantof the choke coil should be greater than that of the rimary coil to permit the above action, In t iis way, the ignition coil may be designed to give an effective spark plug current at the-higher frequencies of operation, thus greatly incres ing the efiiciency of the ignition s stem.

mary circuit are produced. Attention is further directed to the fact that while there are three circuits shown all physically disconnected, suclfdisconnection is not essential for the utilization of the invention, the requisite being that the circuits be conductively related.

I am aware that the various embodiments of my invention as here shown and described, are susceptible of considerable variation without departing v from the spirit of my invention, and, therefore, I desire to claim the same broadly as well as specifically, as indicated the appended claims.

-Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is I -1. In an ignition system, the combination of theprimar'y circuit. adapted to convey a periodically varying current, a secondary circuit inductively related thereto and means including an inde )endent tertiary circuit magnetically in serles with the primary circuit ,for maintaining an approximately con-v stant induced electromotive force in said secondary circuit depending upon the frequency at low speeds, depending upon the frequency The invention has been desc i ed specifi of the primary current. r

In testimony whereof, I aflix my signature.

HENRY R. DAVIES. 

